1 . Technical Field
The present invention relates to zinc alloy electroplating baths, and to a novel brightening agent for such electroplating baths.
2 . Description of the Prior Art
Early work in the area of zinc alloy electroplating is disclosed in U.S. Pat. Nos. 2,080,479; 2,080,483; and 2,083,520, all assigned to E. I. DuPont de Nemours & Company. These patents relate to alkaline zinc and zinc alloy plating baths which contain cyanide. In U.S. Pat. No. 2,080,483, the bath also contains a thiourea. It is suggested in the '483 patent that the thiourea in combination with a group VIII metal exercises a synergetic effect to provide a brightness greater than that attributable to the use of a thiourea in an alloy-free zinc plating bath, or to a zinc alloy bath free of thiourea.
U.S. Pat. No. 4,581,110 discloses an alkaline cyanide-free zinc iron alloy plating bath. The bath contains, as a brightening agent, an aromatic aldehyde mixed with an amine reacted with epichlorohydrin.
Other known brightening agents for zinc and zinc alloy plating baths include sodium saccharin, anisic aldehyde, polyvinyl alcohol, polyethyleneimine, n-benzyl nicotinic acid (sodium salt), benzylidene acetone, and derivatives of polyethylene glycol.
Ureylene quaternary ammonium polymers are well known and have been assigned CAS Registry No. 68555-36-2. They are also disclosed in U.S. Pat. No. 4,157,388. They are sold by Miranol Chemical Company, Inc., a division of Ashland Chemical Company, under the trademark "MIRAPOL". They are conventionally used in such applications as cosmetics, hair and skin conditioners, cleaning compositions, and the retardation of scale in brine solutions.